The Wagtails are so named due to the habit of continuously pumping their tails while at rest and walking about. They, along with pipits, belong to the family Motacillidae which has members distributed throughout the world except in the Pacific Islands. Ten members of this family have been recorded from Sri Lanka. Six of whom are wagtails. All the wagtails recorded from Sri Lanka are winter migrants and 3 of them are common regular visitors that can be seen in many areas of the country during the season. The most widely known of these is the Grey Wagtail that has a wide distribution through Asia, Africa and Europe. In Sinhala, it is called Alu-Helapenda, Helapenda and Halanpenda (all these names refer to the tail wagging habits) and was well-known to farmers as a heralder of the North-East Monsoon.

The Grey Wagtail (Motacilla cinerea) is about 18 cm (7 inches) in length, or slightly larger than a House Sparrow. It is of a slender build and the long tail accounts for half the body length. The beak is short, slender and painted and the legs long. The wings are long and narrow and the narrow tail show the same width all along in length. The body is always carried in a lateral positive and parallel to the ground. In the winter plumage, as it is usually seen in Sri Lanka, the upper parts are dark, clear grey. A thin white brow or supercilium runs just above the eye chin and throat white. Breast and abdomen are a bright lemon yellow that darkens towards the vent. The central tail feathers are black and those in the sides are white. The rump is yellow or greyish yellow and can be seen clearly in flight. In summer plumage, which can be sometimes seen on newly arrived birds or in those about to depart after the stay, the underparts show a deeper and brighter yellow white the upper parts have a bluish tinge. The males develop a black colour on the chin and throat, separated by a thin white line from the grey cheeks.

It is one of the earliest winter migrants to arrive each year and always arrive just before the pre-monsoonal rains. My observations on its arrival, made first in the Ampara District and then in other areas have shown that the Grey Wagtails arrive 2 to 3 weeks before the outbreak of pre-monsoonal rains which are also known as thundershowers. They usually arrive in early September, but in late August in some years. My series of observations on this relationship was prompted by a farmer who told me about it and how they had relied on its arrival to start land preparation for the Maha season. This was stated by other farmers as well and it was seen that all of them have came to the district from the Uva Province where this species is a common presence during the migratory period. In earlier times, it is the arrival of certain migrants such as the Grey Wagtail that had indicated to the farmers that it was time to start land preparation for the forthcoming maha cultivation season in anticipation of the coming north-eastern monsoon W. W. A. Phillips (1955) in his Birds of Ceylon — volume 3 (Birds of our Highlands) has stated that the advent of the Grey Wagtail is looked forward to in Ceylon almost as eagerly as in England the arrival of the Common Swallow — the harbinger of warmer spring weather is welcomed. The Grey Wagtail, however, heralds the coming of our cold weather. This year, the Grey Wagtail came in early September, confirming the relationship once again.

Upon arrival, many individuals spend several days in coastal areas before moving inland. It prefers areas with some shade and water, such as banks of rivers, canals or streams, rocky streams, rivulets in forests, homesteads, tea estates, and in open places like paddy fields, grass lands. It walks fast, nimbly and lightly, dextrously moving among rocks and boulders, making an occasional jump between rocks. The long tail is moved up and down continuously, slowly while at rest or walking but fast and vigorously when exited. It is a restless bird that is continuously on the move throughout the day. It is usually solitary during the stay here, but an occasional pair can be seen. Each bird or pair maintain a territory that is guarded not only against other wagtails but other small birds as well. It makes a sudden dash at intruders to frighten them away but an actual attack was never seen.

The flight is strong, fast and undulating. It flaps the wings several times in quick succession to lift itself and then closes them so that it makes a long graceful dip which is followed by another bout of flapping and a lift. While at flight, a short, sharp "chik-chik" note is uttered constantly. Food consist mainly of small insects, worms and other creatures picked up from the ground, but many jump up and capture insects that takes to flight. At times, one may be seen making short sorties in pursuit of flying insects and return to the same place. In the evening, it leaves the territory to spend the night on a tree, bush, a bed of tall grasses or reeds or even atop a roof of a building. They tend so roost together and large gatherings are seen in the Dry Zone, which are often made up of other species of wagtails as well.

During the stay in Sri Lanka, the Grey Wagtail is commonest in the hills. It ascends to the highest elevations and is seen in considerable numbers in Nuwara Eliya and Horton Plains. It is similarly common in the Uva hills. In the low country wet zone, it is mainly seen in passage, often at the beginning of the migration for a few days before departing to the interior of the country. A few remain throughout the season in jungle streams and ponds. In the dry zone, in contrast it is seen in considerable numbers throughout the season. It leaves Sri Lanka in late March and April.

The Grey Wagtail can be confused with the Yellow Wagtail (Motacilla flava) because both are quite similar in size and shape, have yellow underparts and pump the tail up and down. The Yellow Wagtail has a proportionately shorter tail and the upper parts are either olive-green or brown during winter but not grey. The rump is similar in colour to the back and not yellow as in the grey wagtail which is one of the best diagnostic features in flight. It also lacks the thin white line (wing-bar) on the secondaries. The underparts can vary in colour from a dirty white, light yellow or a dark, bright yellow.